Trigger mechanism for firearms



- Oct. 20, 1959 H. KENNERLEY-TAYLER 2,999,100

TRIGGER MECHANISM FOR FIREARMS 2 Sheets-Sheet 1 Filed Dec. 11, 1957 FIG.

Inventor fl'oraee KenneI'Ze -Eykr 3, W M w,

Oct. 20, 1959 H. KENNERLEY-TAYLER 2 5 TRIGGER MECHANISM FOR FIREARMS Filed Dec. 11, 1957 2 Sheets-Sheet 2 Inventor J1 orace fermerzey x7391?! United States PatentOfiice V Patented Oct. 20, 1959 TRIGGER MECHANISM FOR FIREARMS Application December 11, 1957,.Serial No. 702,101

Claims priority, application Great Britain December 14, 1956 "1 Claim. (Cl. 89-140) This invention relates to trigger mechanism for firearms and is concerned with an improved form of mechanism intended for use in firearms designed to provideeither repetitive or sustained fire with the rapid switching from one form of firing to the other. 7

These mechanisms consist essentially of a trigger which acts through a scar and related parts upon the breech block of the firearm, the reaction of the breech block and hence the form of firing of the firearm being controlled by a fire selector lever which acts upon the component parts of the trigger mechanism to modify their mode of operation.

The invention is concerned with the provision of a simple trigger mechanism of this type which has few working parts.

In accordance with this invention, a trigger mechanism for automatic firearms comprises a pivotally mounted trigger, a pivotally mounted sear arranged so as also to be capable of transitional movement whereby it may become disconnected from the trigger. The mechanism is provided with means exerting a pressure loading upon the sear, which loading attemptsto move the sear away from the trigger and into the path of travel of the breech block, firing pin or other movable part of the gun which normally engages the sear and can move it transitionally against the action of the pressure loading means. The mechanism also has a fire selector lever which is movable into one setting to restrain movement of the sear to prevent the firing of the gun, into a second setting to permit the trigger to operate the sear for single shot firing, and into a third setting where operation of the trigger will cause the sear to permit automatic firing of the gun. I v

Preferably the sear pivot engages in a slot in the scar and the translational movement of the sear is effected by the sliding of the sear about the pivot, while either the trigger or the sear contains a housing containing a spring loaded plunger which exerts the interacting pressure on the other part.

Further the fire selector lever part has surfaces which, when the part is rotated, exert pressure on and thus vary the reaction of the sear to movement imparted to the trigger. 7

According to a feature of the invention, a trigger mechanism for providing either continuous or single shot firing comprises a pivoted trigger, a scar mounted on a pivot so that it can undergo both translational and rotational movement about the pivot and is able to take up a position in which it restrains the movement of the breech block, means for exerting between the trigger and the sear an interacting pressure which attempts to move the sear away from the trigger,-a heel on the trigger which can engage the sear so that the pulling of the trigger causes the sear to be moved so as to not obstruct the breech, and a pivoted fire selector lever part which when in a continuous fire position limits the movement of the sear away from the trigger so that while the trigger is pulled the sear is held engaged by thetrigger heel in a position in which it does not obstruct thebreech, and which when in a single shotfiring position permits the sear 'to be moved backwards away from the trigger after the breech block has been released and then be pushed forward by the breech block on its next forward movement to jamb the sear against the trigger in a position in which it cannot engage the trigger heel until the trigger is released and pulled again.

A trigger mechanism in accordance with the invention will now be described, by way of example, with reference to the accompanying drawings in which:

Figures 1 to 4 are sectional elevations showing the relative positions of the trigger mechanism components when the change lever part is consecutively placed in one of the .safe, single sho continued trigger pull and automatic fire positions. I

Figure 5 shows an end view of the trigger mechanism when the change lever part is placed in the safe position.

Figures 1 and 5 of the accompanying drawings show the relative positions of the trigger mechanism components when the fire selector lever is placed in the nonoperating or safe position and when no extraneous breech block pressure is exerted on the trigger mechanism owing to the breech block being in the forward'unco'cked position. As shown in the figures a trigger 1, having up: per and lower trigger heels 2 and 3 respectively, is pivotally mounted on a trigger axis pin 4 which is located in side plates 5 and 6 secured by a rivet 7 to a spacing block 8. A sear 9, having a sear head 10, an axis slot 11 and a scar toe 12, is mounted on a scar axis pin 13 below the breech in the main body of the firearm (not shown). A breech block 14 having a sear notch 15 is shown in its forward (uncooked) position. The sear 9 which is shown abutting against a gun casing stop face 16 has a pair o f parallel sear lugs 17 and 17a spaced about a shoulder surface 18, and contains housing 19 having a bore 37 for a helical spring 20 which is enlarged at-one end for retention at the closed end of the housing 19 and which is anchored at the open end of the housing to a plunger 21 partly contained in the said housing and located at its free end in a retaining cavity 22 in the lower trigger heel 3. A fire selector lever 23 has an axis pin 24 (Fig. 5) passing through the side plates 5 and 6 and carrying an integral follower 25 having an arm 26, a shoulder 27 and a pair of parallel lugs 28, one only of which is shown in the drawings. The follower 25 has a bore 38 to receive a helical spring 29 and a plunger 30 having a beveled nose 39 which partly encloses the spring. The plunger 30 is forced by the spring into abutment with a trigger stop block 31 having two aligned retaining grooves 32 and 33 and secured by rivets 34 and 35 within the trigger mechanism side plates 5 and 6. A back stop 36 forthe fire selector lever follower 25 is also located in the side plates 5 and 6.

The relative positions of the trigger 1, the 'sear 9 and the fire selector lever follower 25 will now be considered withthe arm 26, which, as shown in'Figure 1, placed in contact with the back stop 36. In this safe position the sear plunger 21 acting on the lower trigger heel 3 causes the sear 9 to be moved axially so that the sear axis pin 13 is against the forward end of the slot 11. The scar is forced into contact with the gun casing stop face 16 and held in that position by contact between the sear lugs 17 and 17a and the change lever follower lugs 28. When the trigger lever 1 is pulled, the upper trigger heel 2 in its rotation about the trigger axis pin 4 makes no contact with the sear toe 12 and consequently no clockwise thrust is exerted about the sear pin 13 on the sear 9, with the result that no depression of the sear head 10 occurs and the head prevents the movement of the breech mechanism to its rearward cocked position. In the event of the fire selector lever 23' being placed into the safe position when the breech mechanism is in its rearward cocked position the sear, will be forced forward over the sear axis pinhy the forward pressure of the. spring loaded breech block and; although the sear toe 12.will then engage? with-the upper trigger heel 2, a pull on the trigger 1 cannot rotate the sear 9, and hence remove the sear head out'of the path of the breech mechanism because of the abutment between the sear lugs 17 and 17a and the changelever followerlugs 28 locks the. sear in this position. s

The action of the mechanism will now be described when positioned as shown 'in Figure 2' wherein the fire selector lever is placed position to permit the trigger to operate the sear for single shot firing and the sear is shown restraining the forward motion of. the spring loaded breech block. When the change lever follower 25 is in this position the plunger 30 is retained in the groove 33 by the pressure of the spring 29 and the fire selector'lever follower is freeof any contact with the sear 9. The breech block 14 which is loaded against the sear head 10 maintains the sear toe 12 in contact with the trigger -'1 and the sear is thus held locked in this position and the forward movement of the breech block is prevented. When the trigger is pulled, the rotation of the upper trigger heel 2 causes a clockwise rotation of the sear 9 about the sear axis pin 13 and the removal of the sear head 10 from the path of the breech block 14 so that the breech block is allowed to move forward above the trigger mechanism' to complete the firing action. At the moment the sear head 10 is disengaged from the breech block the sear moves rearwards over the sear axis pin 13 to the full extent of' the axis slot 11 and also rotates in a counterclockwise direction under the rearward thrust exerted by the helical spring 20 leaving the sear head 10 erected in the path of the breech block. When the breech block is returned rearwards by blow back action it momentarily depresses thew sear 9 but due to the rearward over-run of the breech block the sear has time to re-erectitself and engage the breech block on its forward rebound.

The position of the relative parts of the mechanism with .the fire selector lever remaining in the single shot position but the trigger being depressed again for cooking is shown in Figure 3. The breech block 14 is shown after it has recoiled and run forward to engage'the sear 9 which has its toe 12 forced against the face of the upper trigger heel'Z. When the trigger 1 is now released the breech block 14 and the sear 9 will move forward until the sear. toe 12 is arrested on the upper trigger heel 2 and the breech block is placed in the cocked position in readiness for firing the next round. Y

The position of the parts of the trigger' mechanism when the fire selector lever is placed in the automatic fire position is'shown'in Figure 4. In this position the shoulder 27 of the fire selector lever follower 25 is brought into contact with the shoulder surface 18 of the sear 9 andthesear head 10 is withdrawn from the breech block sear notch by the rotation of the upper trigger heel against the sear toe 12'thus allowing the breech block to travel forward. Whilst the trigger is pulled to its rearward position the sear head 10 will remain depressed out of the path of the breech block and the firearm will continue automatic firing. The sear 9 is restrained from moving out of engagement with the trigger and the sear toe 12 and trigger heel 2 are maintained in engagement by the pressure exerted between the shoulder 27 and the sear shoulder surface 118.

The above described trigger mechanism may be easily dismantled by pushing through the body of the assembly the trigger axis pin 4 and the sear axis pin 13, when it is found that there are only two other loose parts, namely the trigger and sear; the sear plunger and spring and the fire selector lever plunger and spring being retained in their respective housings by the enlarged end turns of the springs.

I claim:

A trigger mechanism for a firearm including a sliding breech block having a scar notch formed on its lower frontal edge thereof, said trigger mechanism comprising a pair of parallel side plates, a trigger pivotally mounted between said plates, said trigger having upper and lower heel portions, an axis pinfixed between said plates rearwardly of said trigger, a sear having an'elongated slot mounted on said axis pin for pivotal and transitional movement thereon, said sear having a forwardly disposed toe portion to engage said upper heel portion of said trigger, an integral head portion adapted to be engaged by said breech block, a pair of spaced integral, rearwardly disposed lugs and a shoulder surface, there being a first bore in said sear, a first springbiased plunger slidable in said first bore in said scar and normally biasing'against said trigger and urging said head on said sear into the path of travel of said breech block, a trigger stop block fixed between said side plates, said block having forward and rearward aligned retaining grooves along its upper edge thereof, a fire selector lever mounted for rotation between said side plates, said fire selector lever defining a pair of forwardly disposed integral lugs for engagement with said stop block, a shoulder portion adapted to abut said shoulder portion on said scar, and a follower having an upstanding integral arm; there being a second bore in said fire selector lever, a second spring-biased plunger having a beveled nose'slidably mounted in said second bore 'in said fire selector lever normally biasing against saidstop block, and a back stop fixed between said side plates for en'- gagement with said arm on said fire selector lever to limit rotational movement of said fire selector lever, said fire selector lever adapted to be rotated into a first position whereby movement of said sear will be restrained to prevent firing of said firearm, a second position whereby said sear is operated to maintain said firearm for semi-automatic firing, and a; third position whereby said sear is operated to maintain said firearm for full automatic firing.

References Cited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS Great Britain Feb. 21, 1944 

